Many strains of the genus Streptomyces produce therapeutically useful substances, such as antibiotics. Some substances useful as the host defense stimulator or immunopotentiator or as the anti-inflammatory agent are known, but there remains a need for a more effective agents useful for therapeutic treatment of various diseases in living animals, including humans.
An object of this invention is to provide new compounds which are useful as the immunopotentiator and/or the anti-inflammatory agent. A further object of this invention is to provide a process for the fermentative production of these new compounds. Other objects will be clear from the following descriptions.
We have made extensively our research in an attempt to produce and obtain new physiologically active compounds. As a result, we have now found that when a new strain of the genus Streptomyces which was isolated from a soil sample collected from the ground of Rissho University in Kumagaya City, Saitama Prefecture, Japan and which was alloted a laboratory designation, Streptomyces MG7-G1 strain, is cultivated in a culture medium under aerobic conditions, there are produced and accumulated in the culture new substances which show the activities inhibitory to esterase and formylmethionine aminopeptidase. We have succeeded to isolate these new substances from the culture and purify them. From the chemical, physical and biological studies of these isolated substances, it has been confirmed that each of these isolated substances is a new compound which is low toxic and which is distinguishable from any of the known compounds. Thus, we have denominated these two new compounds as ebelactone A and ebelactone B, respectively. Ebelactones A and B have the new chemical structures and physico-chemical properties as described later.